Use interfaces in templates.

Perspex.Controls/Primitives/TemplatedControl.cs

@@ -138,8 +138,8 @@ namespace Perspex.Controls.Primitives
                     this.templateLog.Verbose("Creating control template");
 
                     var child = this.Template.Build(this);
-                    this.SetTemplatedParent(child);
-                    this.AddVisualChild(child);
+                    this.SetTemplatedParent((Control)child);
+                    this.AddVisualChild((Visual)child);
                     ((ISetLogicalParent)child).SetParent(this);
 
                     foreach (var i in this.GetTemplateChildren())

Perspex.Controls/Templates/ControlTemplate.cs

@@ -13,13 +13,13 @@ namespace Perspex.Controls.Templates
     /// <summary>
     /// A template for a <see cref="TemplatedControl"/>.
     /// </summary>
-    public class ControlTemplate : FuncTemplate<ITemplatedControl, Control>, IControlTemplate
+    public class ControlTemplate : FuncTemplate<ITemplatedControl, IControl>, IControlTemplate
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="ControlTemplate"/> class.
         /// </summary>
         /// <param name="build">The build function.</param>
-        public ControlTemplate(Func<ITemplatedControl, Control> build)
+        public ControlTemplate(Func<ITemplatedControl, IControl> build)
             : base(build)
         {
         }

Perspex.Controls/Templates/ControlTemplate`2.cs

@@ -20,7 +20,7 @@ namespace Perspex.Controls.Templates
         /// Initializes a new instance of the <see cref="ControlTemplate{T}"/> class.
         /// </summary>
         /// <param name="build">The build function.</param>
-        public ControlTemplate(Func<T, Control> build)
+        public ControlTemplate(Func<T, IControl> build)
             : base(x => build((T)x))
         {
         }

Perspex.Controls/Templates/DataTemplate`1.cs

@@ -20,7 +20,7 @@ namespace Perspex.Controls.Templates
         /// <param name="build">
         /// A function which when passed an object of <typeparamref name="T"/> returns a control.
         /// </param>
-        public DataTemplate(Func<T, Control> build)
+        public DataTemplate(Func<T, IControl> build)
             : base(typeof(T), CastBuild(build))
         {
         }
@@ -34,7 +34,7 @@ namespace Perspex.Controls.Templates
         /// <param name="build">
         /// A function which when passed an object of <typeparamref name="T"/> returns a control.
         /// </param>
-        public DataTemplate(Func<T, bool> match, Func<T, Control> build)
+        public DataTemplate(Func<T, bool> match, Func<T, IControl> build)
             : base(CastMatch(match), CastBuild(build))
         {
         }

Perspex.Controls/Templates/IControlTemplate.cs

@@ -12,7 +12,7 @@ namespace Perspex.Controls.Templates
     /// <summary>
     /// Interface representing a template used to build a <see cref="TemplatedControl"/>.
     /// </summary>
-    public interface IControlTemplate : ITemplate<ITemplatedControl, Control>
+    public interface IControlTemplate : ITemplate<ITemplatedControl, IControl>
     {
     }
 }